My father is 83 years old and has studied trading for almost 52 years.
He summarized some simple rules for beginners:
1. Price falls 5% ..Hold
2. Price falls 15% ..Buy 10%
3. Price falls 25% ..Buy 25%
4. Price rises 5% ..Continue holding
5. Price rises 15% ..Continue holding
6. Price rises 25% .. Sell 10%
7. Price rises 35% ..Sell 20%
8. Price rises 45% ..Sell 30%
9. Price rises 60% .. Sell 40%
10. Price rises 100% .. Sell everything
Discipline + patience .. stable long-term growth.
(Save this later).